flat address space


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flat address space

(architecture)
The memory architecture in which any memory location can be selected from a single contiguous block by a single integer offset.

Almost all popular processors have a flat address space, but the Intel x86 family has a segmented address space. A flat address space greatly simplifies programming because of the simple correspondence between addresses (pointers) and integers.

flat address space

Memory (RAM) that is addressed starting with 0, and each subsequent byte is referenced by the next sequential number (1, 2, 3, etc.). A 32-bit computer with a 32-bit address space treats all 4GB of memory (its maximum) as one contiguous segment. However, a 64-bit address register can hold a gigantic number, and 64-bit motherboards limit the maximum memory typically to 128GB (see binary values).

In contrast, the 16-bit mode (Real Mode) in an x86 PC uses a segmented address space. Memory is broken up into 64KB segments, and a segment register is always being adjusted to point to the base of the segment that is currently being addressed. See Real Mode and address register.